For transport (and storage), if you have access to foam trays, then (aluminium) tool cases can often be bought very cheaply in DIY stores. They come with some inserts for dividing the innards of the case, which can be positioned to keep the trays in place.
I would use that solution, were cheap foam trays only available here in DK, but I have to order them from the UK, and then postage makes it not worth while (cost nearing the price of GW cases....).